Phosphorus is an essential element of life. Usually, it is bound with oxygen and other minerals to form phosphates.
However, when high levels of phosphates are found in your pond, the chances of your pond having issues with algae blooms increase. On the other hand, when phosphate levels are kept low, then algae growth will be limited.
Where do phosphates come from?
One primary source is the tap water used to fill ponds. Not only can phosphates be found in the rivers used for water supplies, but phosphates are added to tap water to reduce pipe corrosion and prevent lead from entering our drinking supply.
Another source is fish food, which contains some phosphorus as it’s an essential part of their diet. A large proportion will pass through the koi, which is released into the fish waste. This waste releases phosphates into the water.
In addition, run-off from lawns, borders, and surrounding paving can wash phosphates into the pond, especially if the garden has had fertilizers applied.
What can I do to prevent high levels of phosphates in my pond?
First and foremost, do not overfeed your koi. Use good quality koi food, and only feed higher-protein ‘growth’ formulas during the summer months.
Also, take a look at the labels on your koi food, as some will list the phosphorus levels. Your food should have 1% or less. If it has more, you may want to look into switching foods.
Design the edges of your pond to prevent run-off from washing in. For example, ensure the edge of your pond is at least six inches above ground level.
Regularly maintain your filtration system. By keeping up on the backwashing of your system, you’ll remove phosphates that are bound to fine particulates in the water. This can prove to be very useful in eliminating the phosphates in your pond.
Last but not least, you can use a chemical to remove the phosphates from your pond. We suggest using Orenda PR-10,000 Phosphate Remover. While designed for pools in mind, we’ve found it safe and successful for use in koi ponds.